Under federal retirement laws, an employer can be held responsible if it is shown the company either actively misled employees regarding their benefits, or if it failed to correct what it knew was a misunderstanding held by employees.
Blue Cross altered its plan in 2001 to require certain retirees, including Leuthner and Reasner, to pay more toward their coverage. And while the plaintiff's acknowledge that Blue Cross advised employees of its ability to alter benefits in legal disclosures included in their plan descriptions, they argue the company also provided other documents that misled employees to mistakenly believe the benefits that were in place when they retired were locked in for life.
Here's a link to the story and here is a related story. Moral of the story: Check your plan documents carefully to make sure they are clear as to the company's rights to modify them in the future. The issues of company's modifications of health and retirement plans is a hot button with jurors, who do not appreciate company's efforts, legal or not, to retroactively reduce benefits that employees believed they would be entitled to for life when they decided to retire.